The present invention relates to an exposure technology. More specifically, it relates to an exposure apparatus and an exposure method each for controlling the application of a charged particle beam or a light on a sample using pattern shape data in a bitmap format, and exposing an LSI pattern, or the like.
Herein, a description will be given taking an exposure apparatus, particularly, an exposure apparatus using a charged particle beam as an example of the prior art.
FIG. 18 shows a general configuration of a charged particle beam lithography system for drawing an LSI pattern or the like (ex., see Sakitani et al.: “E-beam cell-projection lithography system”, J. Vac. Sci. Technol. B, Vol. 10, No.6, November/December, 1992).
In the figure, a reference numeral 1801 denotes a charged beam housing; and 1802, a charged beam source, which generates a charged beam 1803. Reference numerals 1804, 1805, and 1806 denote a deflector/lens group, which converges and deflects the charged beam 1803. A sample 1807 on which a pattern is drawn is placed on a sample stage 1808. Further, the sample stage 1808 is position controlled by means of a sample stage control system 1811 including a laser length measuring instrument 1809. A reference numeral 1812 denotes a deflector/lens control system; 1813, a data control system; 1814, a control computer; and each of 1815, 1816, and 1817, a deflector/lens driver circuit. A pattern data to be drawn is inputted from the control computer 1814, and processed at the data control system 1813. Based on the result, the deflector/lens control system 1812 drives the deflector/lens group 1804, 1805, and 1806 via the deflector/lens driver circuits 1815, 1816, and 1817, and converges and deflects the charged beam 1803 to carry out drawing on the sample 1807.
FIG. 1 shows a prior-art data processing process in a charged particle beam lithography system for controlling the application of a charged particle beam on a sample using pattern shape data in a bitmap format, and drawing an LSI pattern or the like (see, ex., Abboud et al.: “Electron beam lithography using MEBES IV”, J. Vac. Sci. Technol. B, Vol. 10, No. 6, November/December, 1992).
In the figure, a data processing unit 101 is composed of a data grouping/line up unit 102, a pattern decomposition unit 103, a quantization unit 104, and a field memory unit 105. A pattern 106 to be inputted to the data processing unit 101 is configured as an aggregate of basic patterns defined by basic pattern commands indicative of rectangles or oblique patterns.
For example, as shown in FIG. 1, the inputted patterns are first classified into groups respectively present inside the areas allowing exposure thereon by beam deflection (deflection areas 1 to 4) at the data grouping/line-up unit 102. Further, the deflection areas are arrayed on a per grouped data basis according to the exposure sequence. Then, the arrayed data are sequentially inputted according to the sequence in which they are arrayed into the pattern decomposition unit 103. Each pattern in each deflection area is further divided into minute rectangles 107 from the basic pattern defined by a basic pattern command. This processing is generally performed on an oblique pattern. By this, every pattern is converted into the format adopting the rectangle 107 as the fundamental unit.
Then, the respective divided rectangles 107 are sequentially inputted to the quantization unit 104, and each size and each coordinates in the deflection area are respectively quantized to the integral multiple of the size of a pixel 108 constituting a bitmap. Then, a processing for assigning value 1 to each pixel included in each rectangle inside area, and value 0 to each pixel included in the outside area is performed to obtain the bitmap for each rectangle. In actuality, to the field memory unit 105 having two dimensional addresses corresponding to the deflection areas, writing is sequentially performed on a per rectangle basis by determining the addresses with reference to the coordinates and the size of each quantized rectangle. By sequentially writing the quantized rectangle data on the field memory, the overlap between patterns is automatically rejected.
By repeatedly performing a series of the processing steps, it is possible to obtain pattern data in the bitmap format for each deflection area on the field memory. The bitmap data obtained are sequentially read in synchronism with deflection control, and supplied for exposure operation control such as blanking control.
The problems encountered during the foregoing prior-art data processing operation are that large bitmap data developed on a per deflection area basis are required to be handled in a high-speed data processing system, and that a large scale memory area for holding the data becomes necessary.
In recent years, the size resolution required of a lithography apparatus has been increasingly becoming smaller. In the prior art bitmap data, the values which the pixels have are simple binary, and hence the pixel size and the size resolution of the lithography system are in a one-to-one relationship to each other. Therefore, in order to make finer the size resolution of the lithography system according to the request, it is necessary to reduce the pixel size of the bitmap itself. As a result, the bitmap data to be developed and held are increasingly becoming larger, resulting in a bottleneck against the high-speed performances of data processing and blanking control. In addition, the memory area further increases in scale, resulting in an increase in scale of the system.